1. Field of the Invention
The invention relates in general to an apparatus to prevent electromagnetic interference (EMI), and more particularly, to an apparatus that has the flux-leaking gap mended to improve the prevention of electromagnetic interference.
2. Description of the Related Art
During the operation of an electrical or an electronic apparatus, electromagnetic radiation often emanates from several parts thereof, including the power source, the transmission conductive line and the electronic component. The emanating electromagnetic radiation results in an electromagnetic interference. The electromagnetic radiation may sometimes be so serious to affect the normal operation of other equipment. Therefore, how to prevent the equipment from being affected by the external electromagnetic interference and how to prevent the operation of equipment from generating electromagnetic interference are very challenging issues to various equipment.
The mechanism of electromagnetic interference prevention is not difficult by enclosing the electrical or electronic device with an appropriate shield, including the highly conductive metal such as copper and iron, or by connecting the electrical or electronic device to ground. The skin effect of the electromagnetic wave causes a part thereof traveling along the shield and gradually decaying. However, once the shield has any defect such as an opening, or once the device is not appropriately grounded, the electromagnetic wave emanates via the opening to cause leakage flux.
After being fabricated, the conventional structure that prevents electromagnetic wave has to be tested before practical application. The flux-leaking gap caused by poor design or imperfect assembly can be inspected. If any minor flux-leaking gap is found, a conductive tape or conductive paste can be applied for mending. Once the flux-leaking gap is too big to mend, the whole mold has to be fixed. The frequent fixture of the mold shortens the lifetime thereof. Sometimes the mold cannot even be fixed. Instead, a new mold has to be made. The formation of the flux-leaking gap is sometimes caused by using a common mold to fabricate the same products designed for different equipment. The different design for different equipment thus causes the formation of the flux-leaking gap.
FIG. 1 shows a shield 10 with a flux-leaking gap. The flux-leaking gap is in a form of an opening 12. FIG. 2 shows a conventional method to mend the flux-leaking gap. An additional metal plate 14 sized according to the dimension of the opening 12 is used to fill the opening 12. A conductive tape 16 is then used to adhere the joints between shield 10 and the metal plate 14, such that the metal plate 14 is fixed to the shield 10. The typical conductive tape 17 includes a paste of which the endurance of temperature variation is not high enough. When the electromagnetic radiation source is operating, the high temperature generated thereby causes the conductive tape 17 to peel off. In addition, the size of the metal plate 14 has to be adjusted according to the dimension of the opening 12.
In FIG. 3, another conventional method for mending the opening is shown. In FIG. 3, a metal plate 18 with a size larger than the opening 12 is required. The periphery of the metal plate 18 is cut into a plurality of legs. The alternate legs are bent, such that a vertical distance between the alternate bent and unbent legs can receive the shield 10 via the opening 12. That is, the opening 12 is filled with the metal plate 18. By this method, the problem for having the conductive tape peeling off from the shield is resolved. However, such structure is easily broken. A part of the electromagnetic wave stills radiate through gaps between the metal plate 18 and the shield 10. Further, the metal plate has to be designed according to the dimension of the opening 12.
The present invention provides a mending apparatus for a flux-leaking gap to enclose the electromagnetic radiation source. The mending apparatus that effectively mends the shield with an opening comprises an additional metal plate and an S-shape common clip. The S-shape common clip is used to connect the shield and the additional metal plate, so as to seal the opening. The S-shape common clip has a first end, a first turning part, a second turning part and a second end. The first turning part extends from the first end and has a turn with an angle of about 180xc2x0, while the second turning part extends from the second end and turns with an angle of about 180xc2x0. The first end and the second end are pointing towards opposing directions with the first and the second turning parts connected to each other therebetween. Thus constructed, the S-shape common clip has a first space and a second space open to two opposing directions formed by the first and the second turning parts. One side of the opening of the shield is thus received in one of the first and second spaces, while the additional metal plate is received in the other of the first and the second spaces. As a result, the additional metal and the shield are connected together without being affected by the temperature variation.
Both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.